I think with gravity, you are probably going to get at least 20% more syrup with 7/16. I have another producer close to me that has high tap counts on laterals, sagging laterals, etc and he always gets significantly more sap than I do and he uses all 7/16" spouts on gravity and I have all my laterals stretched tight, use mainlines which he doesn't and etc and he still gets a lot more sap.

Vacuum, I don't think it will make much of a difference.